What is chikungunya?

Beware Aedes albopictus, otherwise known as the Asian tiger mosquito. (Photo: James Gathany/CDC)

Before mid-July of 2014, there were 357 cases of chikungunya infection in the United States, all acquired by mosquito-bitten travelers outside of the country. But with the recent announcement by health officials that a Florida man and woman – who had not recently traveled – had become infected, we now have the first indication that the vexing virus has taken up residence in the States.

Long known in Asia, Africa and Europe, chikungunya (pronounced chick-un-goon-ya) virus is spread to people by Aedes aegypti and Ae. albopictus (commonly known as the Asian tiger mosquito), the same pesky pests that introduced us to dengue fever. But unlike dengue fever, chikungunya does not require a “reservoir” and is spread directly from one human host to another via mosquito. Other mosquito-borne pathogens, like West Nile virus, must replicate inside a bird before they can pass from a mosquito to a human, according to Slate, which calls chikungunya the virus that makes entomologists nervous.

The fact that Asian tiger mosquitoes, in particular, can spread the disease is a cause for concern amongst some experts; these mosquitoes target humans for feeding (many mosquitoes prefer other animals) and they eat during the day, when unsuspecting humans are at their most active. Not to mention that these aggressive biters are intrepid insects – originally from Southeast Asia, they are listed on the Global Invasive Species Database as one of the 100 worst invasive alien species. Introduced to the U.S. in 1985, the species has now spread to most areas east of the Mississippi and they are not that fussy in terms of breeding environments.

Ann Powers, research microbiologist and chief of the Alphavirus Laboratory in CDC’s Division of Vector-Borne Diseases, describes chikungunya as a virus with the potential to spread "sickness and misery" in the U.S.

“While chikungunya does not kill people, the toll it inflicts ranks high on the misery index; it hits fast and hard and with almost no subtlety,” she says. “People infected with chikungunya typically experience high fever and severe joint pain soon after they are exposed. Sometimes those problems are long-lasting.”

Symptoms
The incubation period from bite to the onset of symptoms is generally three to seven days (although the official range is one to 12 days) and is most often characterized by high fever, typically above 102 degrees.

Joint pain, the other most common symptom, has been described as “fiercely unpleasant.” The pain can be severe and debilitating. Other symptoms may include headache, muscle pain, joint swelling or rash.

Rare complications — including unpleasantries like hepatitis, nephritis, bullous skin lesions, hemorrhage, meningoencephalitis and myelitis — are also known to occur. Newborn babies, older adults and people with underlying medical conditions (hypertension, diabetes, or cardiovascular disease) are at higher risk for severe disease.

Fortunately, the worst of it should typically pass within seven to 10 days, although for some people the joint pain can persist for months or even years. Once infected, a person is likely to be immune to future infection from the virus. So, at least there’s that.

Another thing to note: dengue fever and chikungunya can present with similar symptoms (and for some truly unfortunate people, occasional co-infections can occur). But chikungunya is more likely to cause high fever, severe joint pain, arthritis and rash, while dengue is more likely to cause neutropenia, thrombocytopenia, hemorrhage, shock and death.

Treatment and prevention
There’s no treatment for the infection; one can only try to decrease the discomfort of the symptoms. The CDC recommends getting plenty of rest, drinking enough fluids to prevent dehydration, and taking medications — like ibuprofen, naproxen, acetaminophen, or paracetamol — to reduce fever and pain.

During the first week of illness, it’s important for anyone infected to avoid being bitten by a mosquito and further spread the disease. And if you happen to be a mosquito magnet, refer to these ways to avoid mosquitoes. For while getting a simple mosquito bite can be maddening, getting a fiercely unpleasant viral infection from one is good reason to do all you can to avoid being bitten in the first place.